Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

[cris-mirror.git] / drivers / net / wireless / intel / iwlegacy / 3945-rs.c

/******************************************************************************
 *
 * Copyright(c) 2005 - 2011 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
 *
 * The full GNU General Public License is included in this distribution in the
 * file called LICENSE.
 *
 * Contact Information:
 *  Intel Linux Wireless <ilw@linux.intel.com>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *
 *****************************************************************************/

#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/mac80211.h>

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/delay.h>

#include <linux/workqueue.h>

#include "commands.h"
#include "3945.h"

#define RS_NAME "iwl-3945-rs"

static s32 il3945_expected_tpt_g[RATE_COUNT_3945] = {
        7, 13, 35, 58, 0, 0, 76, 104, 130, 168, 191, 202
};

static s32 il3945_expected_tpt_g_prot[RATE_COUNT_3945] = {
        7, 13, 35, 58, 0, 0, 0, 80, 93, 113, 123, 125
};

static s32 il3945_expected_tpt_a[RATE_COUNT_3945] = {
        0, 0, 0, 0, 40, 57, 72, 98, 121, 154, 177, 186
};

static s32 il3945_expected_tpt_b[RATE_COUNT_3945] = {
        7, 13, 35, 58, 0, 0, 0, 0, 0, 0, 0, 0
};

struct il3945_tpt_entry {
        s8 min_rssi;
        u8 idx;
};

static struct il3945_tpt_entry il3945_tpt_table_a[] = {
        {-60, RATE_54M_IDX},
        {-64, RATE_48M_IDX},
        {-72, RATE_36M_IDX},
        {-80, RATE_24M_IDX},
        {-84, RATE_18M_IDX},
        {-85, RATE_12M_IDX},
        {-87, RATE_9M_IDX},
        {-89, RATE_6M_IDX}
};

static struct il3945_tpt_entry il3945_tpt_table_g[] = {
        {-60, RATE_54M_IDX},
        {-64, RATE_48M_IDX},
        {-68, RATE_36M_IDX},
        {-80, RATE_24M_IDX},
        {-84, RATE_18M_IDX},
        {-85, RATE_12M_IDX},
        {-86, RATE_11M_IDX},
        {-88, RATE_5M_IDX},
        {-90, RATE_2M_IDX},
        {-92, RATE_1M_IDX}
};

#define RATE_MAX_WINDOW         62
#define RATE_FLUSH              (3*HZ)
#define RATE_WIN_FLUSH          (HZ/2)
#define IL39_RATE_HIGH_TH       11520
#define IL_SUCCESS_UP_TH        8960
#define IL_SUCCESS_DOWN_TH      10880
#define RATE_MIN_FAILURE_TH     6
#define RATE_MIN_SUCCESS_TH     8
#define RATE_DECREASE_TH        1920
#define RATE_RETRY_TH           15

static u8
il3945_get_rate_idx_by_rssi(s32 rssi, enum nl80211_band band)
{
        u32 idx = 0;
        u32 table_size = 0;
        struct il3945_tpt_entry *tpt_table = NULL;

        if (rssi < IL_MIN_RSSI_VAL || rssi > IL_MAX_RSSI_VAL)
                rssi = IL_MIN_RSSI_VAL;

        switch (band) {
        case NL80211_BAND_2GHZ:
                tpt_table = il3945_tpt_table_g;
                table_size = ARRAY_SIZE(il3945_tpt_table_g);
                break;
        case NL80211_BAND_5GHZ:
                tpt_table = il3945_tpt_table_a;
                table_size = ARRAY_SIZE(il3945_tpt_table_a);
                break;
        default:
                BUG();
                break;
        }

        while (idx < table_size && rssi < tpt_table[idx].min_rssi)
                idx++;

        idx = min(idx, table_size - 1);

        return tpt_table[idx].idx;
}

static void
il3945_clear_win(struct il3945_rate_scale_data *win)
{
        win->data = 0;
        win->success_counter = 0;
        win->success_ratio = -1;
        win->counter = 0;
        win->average_tpt = IL_INVALID_VALUE;
        win->stamp = 0;
}

/**
 * il3945_rate_scale_flush_wins - flush out the rate scale wins
 *
 * Returns the number of wins that have gathered data but were
 * not flushed.  If there were any that were not flushed, then
 * reschedule the rate flushing routine.
 */
static int
il3945_rate_scale_flush_wins(struct il3945_rs_sta *rs_sta)
{
        int unflushed = 0;
        int i;
        unsigned long flags;
        struct il_priv *il __maybe_unused = rs_sta->il;

        /*
         * For each rate, if we have collected data on that rate
         * and it has been more than RATE_WIN_FLUSH
         * since we flushed, clear out the gathered stats
         */
        for (i = 0; i < RATE_COUNT_3945; i++) {
                if (!rs_sta->win[i].counter)
                        continue;

                spin_lock_irqsave(&rs_sta->lock, flags);
                if (time_after(jiffies, rs_sta->win[i].stamp + RATE_WIN_FLUSH)) {
                        D_RATE("flushing %d samples of rate " "idx %d\n",
                               rs_sta->win[i].counter, i);
                        il3945_clear_win(&rs_sta->win[i]);
                } else
                        unflushed++;
                spin_unlock_irqrestore(&rs_sta->lock, flags);
        }

        return unflushed;
}

#define RATE_FLUSH_MAX              5000        /* msec */
#define RATE_FLUSH_MIN              50  /* msec */
#define IL_AVERAGE_PACKETS             1500

static void
il3945_bg_rate_scale_flush(struct timer_list *t)
{
        struct il3945_rs_sta *rs_sta = from_timer(rs_sta, t, rate_scale_flush);
        struct il_priv *il __maybe_unused = rs_sta->il;
        int unflushed = 0;
        unsigned long flags;
        u32 packet_count, duration, pps;

        D_RATE("enter\n");

        unflushed = il3945_rate_scale_flush_wins(rs_sta);

        spin_lock_irqsave(&rs_sta->lock, flags);

        /* Number of packets Rx'd since last time this timer ran */
        packet_count = (rs_sta->tx_packets - rs_sta->last_tx_packets) + 1;

        rs_sta->last_tx_packets = rs_sta->tx_packets + 1;

        if (unflushed) {
                duration =
                    jiffies_to_msecs(jiffies - rs_sta->last_partial_flush);

                D_RATE("Tx'd %d packets in %dms\n", packet_count, duration);

                /* Determine packets per second */
                if (duration)
                        pps = (packet_count * 1000) / duration;
                else
                        pps = 0;

                if (pps) {
                        duration = (IL_AVERAGE_PACKETS * 1000) / pps;
                        if (duration < RATE_FLUSH_MIN)
                                duration = RATE_FLUSH_MIN;
                        else if (duration > RATE_FLUSH_MAX)
                                duration = RATE_FLUSH_MAX;
                } else
                        duration = RATE_FLUSH_MAX;

                rs_sta->flush_time = msecs_to_jiffies(duration);

                D_RATE("new flush period: %d msec ave %d\n", duration,
                       packet_count);

                mod_timer(&rs_sta->rate_scale_flush,
                          jiffies + rs_sta->flush_time);

                rs_sta->last_partial_flush = jiffies;
        } else {
                rs_sta->flush_time = RATE_FLUSH;
                rs_sta->flush_pending = 0;
        }
        /* If there weren't any unflushed entries, we don't schedule the timer
         * to run again */

        rs_sta->last_flush = jiffies;

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        D_RATE("leave\n");
}

/**
 * il3945_collect_tx_data - Update the success/failure sliding win
 *
 * We keep a sliding win of the last 64 packets transmitted
 * at this rate.  win->data contains the bitmask of successful
 * packets.
 */
static void
il3945_collect_tx_data(struct il3945_rs_sta *rs_sta,
                       struct il3945_rate_scale_data *win, int success,
                       int retries, int idx)
{
        unsigned long flags;
        s32 fail_count;
        struct il_priv *il __maybe_unused = rs_sta->il;

        if (!retries) {
                D_RATE("leave: retries == 0 -- should be at least 1\n");
                return;
        }

        spin_lock_irqsave(&rs_sta->lock, flags);

        /*
         * Keep track of only the latest 62 tx frame attempts in this rate's
         * history win; anything older isn't really relevant any more.
         * If we have filled up the sliding win, drop the oldest attempt;
         * if the oldest attempt (highest bit in bitmap) shows "success",
         * subtract "1" from the success counter (this is the main reason
         * we keep these bitmaps!).
         * */
        while (retries > 0) {
                if (win->counter >= RATE_MAX_WINDOW) {

                        /* remove earliest */
                        win->counter = RATE_MAX_WINDOW - 1;

                        if (win->data & (1ULL << (RATE_MAX_WINDOW - 1))) {
                                win->data &= ~(1ULL << (RATE_MAX_WINDOW - 1));
                                win->success_counter--;
                        }
                }

                /* Increment frames-attempted counter */
                win->counter++;

                /* Shift bitmap by one frame (throw away oldest history),
                 * OR in "1", and increment "success" if this
                 * frame was successful. */
                win->data <<= 1;
                if (success > 0) {
                        win->success_counter++;
                        win->data |= 0x1;
                        success--;
                }

                retries--;
        }

        /* Calculate current success ratio, avoid divide-by-0! */
        if (win->counter > 0)
                win->success_ratio =
                    128 * (100 * win->success_counter) / win->counter;
        else
                win->success_ratio = IL_INVALID_VALUE;

        fail_count = win->counter - win->success_counter;

        /* Calculate average throughput, if we have enough history. */
        if (fail_count >= RATE_MIN_FAILURE_TH ||
            win->success_counter >= RATE_MIN_SUCCESS_TH)
                win->average_tpt =
                    ((win->success_ratio * rs_sta->expected_tpt[idx] +
                      64) / 128);
        else
                win->average_tpt = IL_INVALID_VALUE;

        /* Tag this win as having been updated */
        win->stamp = jiffies;

        spin_unlock_irqrestore(&rs_sta->lock, flags);
}

/*
 * Called after adding a new station to initialize rate scaling
 */
void
il3945_rs_rate_init(struct il_priv *il, struct ieee80211_sta *sta, u8 sta_id)
{
        struct ieee80211_hw *hw = il->hw;
        struct ieee80211_conf *conf = &il->hw->conf;
        struct il3945_sta_priv *psta;
        struct il3945_rs_sta *rs_sta;
        struct ieee80211_supported_band *sband;
        int i;

        D_INFO("enter\n");
        if (sta_id == il->hw_params.bcast_id)
                goto out;

        psta = (struct il3945_sta_priv *)sta->drv_priv;
        rs_sta = &psta->rs_sta;
        sband = hw->wiphy->bands[conf->chandef.chan->band];

        rs_sta->il = il;

        rs_sta->start_rate = RATE_INVALID;

        /* default to just 802.11b */
        rs_sta->expected_tpt = il3945_expected_tpt_b;

        rs_sta->last_partial_flush = jiffies;
        rs_sta->last_flush = jiffies;
        rs_sta->flush_time = RATE_FLUSH;
        rs_sta->last_tx_packets = 0;

        for (i = 0; i < RATE_COUNT_3945; i++)
                il3945_clear_win(&rs_sta->win[i]);

        /* TODO: what is a good starting rate for STA? About middle? Maybe not
         * the lowest or the highest rate.. Could consider using RSSI from
         * previous packets? Need to have IEEE 802.1X auth succeed immediately
         * after assoc.. */

        for (i = sband->n_bitrates - 1; i >= 0; i--) {
                if (sta->supp_rates[sband->band] & (1 << i)) {
                        rs_sta->last_txrate_idx = i;
                        break;
                }
        }

        il->_3945.sta_supp_rates = sta->supp_rates[sband->band];
        /* For 5 GHz band it start at IL_FIRST_OFDM_RATE */
        if (sband->band == NL80211_BAND_5GHZ) {
                rs_sta->last_txrate_idx += IL_FIRST_OFDM_RATE;
                il->_3945.sta_supp_rates <<= IL_FIRST_OFDM_RATE;
        }

out:
        il->stations[sta_id].used &= ~IL_STA_UCODE_INPROGRESS;

        D_INFO("leave\n");
}

static void *
il3945_rs_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
{
        return hw->priv;
}

/* rate scale requires free function to be implemented */
static void
il3945_rs_free(void *il)
{
}

static void *
il3945_rs_alloc_sta(void *il_priv, struct ieee80211_sta *sta, gfp_t gfp)
{
        struct il3945_rs_sta *rs_sta;
        struct il3945_sta_priv *psta = (void *)sta->drv_priv;
        struct il_priv *il __maybe_unused = il_priv;

        D_RATE("enter\n");

        rs_sta = &psta->rs_sta;

        spin_lock_init(&rs_sta->lock);
        timer_setup(&rs_sta->rate_scale_flush, il3945_bg_rate_scale_flush, 0);
        D_RATE("leave\n");

        return rs_sta;
}

static void
il3945_rs_free_sta(void *il_priv, struct ieee80211_sta *sta, void *il_sta)
{
        struct il3945_rs_sta *rs_sta = il_sta;

        /*
         * Be careful not to use any members of il3945_rs_sta (like trying
         * to use il_priv to print out debugging) since it may not be fully
         * initialized at this point.
         */
        del_timer_sync(&rs_sta->rate_scale_flush);
}

/**
 * il3945_rs_tx_status - Update rate control values based on Tx results
 *
 * NOTE: Uses il_priv->retry_rate for the # of retries attempted by
 * the hardware for each rate.
 */
static void
il3945_rs_tx_status(void *il_rate, struct ieee80211_supported_band *sband,
                    struct ieee80211_sta *sta, void *il_sta,
                    struct sk_buff *skb)
{
        s8 retries = 0, current_count;
        int scale_rate_idx, first_idx, last_idx;
        unsigned long flags;
        struct il_priv *il = (struct il_priv *)il_rate;
        struct il3945_rs_sta *rs_sta = il_sta;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

        D_RATE("enter\n");

        retries = info->status.rates[0].count;
        /* Sanity Check for retries */
        if (retries > RATE_RETRY_TH)
                retries = RATE_RETRY_TH;

        first_idx = sband->bitrates[info->status.rates[0].idx].hw_value;
        if (first_idx < 0 || first_idx >= RATE_COUNT_3945) {
                D_RATE("leave: Rate out of bounds: %d\n", first_idx);
                return;
        }

        if (!il_sta) {
                D_RATE("leave: No STA il data to update!\n");
                return;
        }

        /* Treat uninitialized rate scaling data same as non-existing. */
        if (!rs_sta->il) {
                D_RATE("leave: STA il data uninitialized!\n");
                return;
        }

        rs_sta->tx_packets++;

        scale_rate_idx = first_idx;
        last_idx = first_idx;

        /*
         * Update the win for each rate.  We determine which rates
         * were Tx'd based on the total number of retries vs. the number
         * of retries configured for each rate -- currently set to the
         * il value 'retry_rate' vs. rate specific
         *
         * On exit from this while loop last_idx indicates the rate
         * at which the frame was finally transmitted (or failed if no
         * ACK)
         */
        while (retries > 1) {
                if ((retries - 1) < il->retry_rate) {
                        current_count = (retries - 1);
                        last_idx = scale_rate_idx;
                } else {
                        current_count = il->retry_rate;
                        last_idx = il3945_rs_next_rate(il, scale_rate_idx);
                }

                /* Update this rate accounting for as many retries
                 * as was used for it (per current_count) */
                il3945_collect_tx_data(rs_sta, &rs_sta->win[scale_rate_idx], 0,
                                       current_count, scale_rate_idx);
                D_RATE("Update rate %d for %d retries.\n", scale_rate_idx,
                       current_count);

                retries -= current_count;

                scale_rate_idx = last_idx;
        }

        /* Update the last idx win with success/failure based on ACK */
        D_RATE("Update rate %d with %s.\n", last_idx,
               (info->flags & IEEE80211_TX_STAT_ACK) ? "success" : "failure");
        il3945_collect_tx_data(rs_sta, &rs_sta->win[last_idx],
                               info->flags & IEEE80211_TX_STAT_ACK, 1,
                               last_idx);

        /* We updated the rate scale win -- if its been more than
         * flush_time since the last run, schedule the flush
         * again */
        spin_lock_irqsave(&rs_sta->lock, flags);

        if (!rs_sta->flush_pending &&
            time_after(jiffies, rs_sta->last_flush + rs_sta->flush_time)) {

                rs_sta->last_partial_flush = jiffies;
                rs_sta->flush_pending = 1;
                mod_timer(&rs_sta->rate_scale_flush,
                          jiffies + rs_sta->flush_time);
        }

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        D_RATE("leave\n");
}

static u16
il3945_get_adjacent_rate(struct il3945_rs_sta *rs_sta, u8 idx, u16 rate_mask,
                         enum nl80211_band band)
{
        u8 high = RATE_INVALID;
        u8 low = RATE_INVALID;
        struct il_priv *il __maybe_unused = rs_sta->il;

        /* 802.11A walks to the next literal adjacent rate in
         * the rate table */
        if (unlikely(band == NL80211_BAND_5GHZ)) {
                int i;
                u32 mask;

                /* Find the previous rate that is in the rate mask */
                i = idx - 1;
                for (mask = (1 << i); i >= 0; i--, mask >>= 1) {
                        if (rate_mask & mask) {
                                low = i;
                                break;
                        }
                }

                /* Find the next rate that is in the rate mask */
                i = idx + 1;
                for (mask = (1 << i); i < RATE_COUNT_3945; i++, mask <<= 1) {
                        if (rate_mask & mask) {
                                high = i;
                                break;
                        }
                }

                return (high << 8) | low;
        }

        low = idx;
        while (low != RATE_INVALID) {
                if (rs_sta->tgg)
                        low = il3945_rates[low].prev_rs_tgg;
                else
                        low = il3945_rates[low].prev_rs;
                if (low == RATE_INVALID)
                        break;
                if (rate_mask & (1 << low))
                        break;
                D_RATE("Skipping masked lower rate: %d\n", low);
        }

        high = idx;
        while (high != RATE_INVALID) {
                if (rs_sta->tgg)
                        high = il3945_rates[high].next_rs_tgg;
                else
                        high = il3945_rates[high].next_rs;
                if (high == RATE_INVALID)
                        break;
                if (rate_mask & (1 << high))
                        break;
                D_RATE("Skipping masked higher rate: %d\n", high);
        }

        return (high << 8) | low;
}

/**
 * il3945_rs_get_rate - find the rate for the requested packet
 *
 * Returns the ieee80211_rate structure allocated by the driver.
 *
 * The rate control algorithm has no internal mapping between hw_mode's
 * rate ordering and the rate ordering used by the rate control algorithm.
 *
 * The rate control algorithm uses a single table of rates that goes across
 * the entire A/B/G spectrum vs. being limited to just one particular
 * hw_mode.
 *
 * As such, we can't convert the idx obtained below into the hw_mode's
 * rate table and must reference the driver allocated rate table
 *
 */
static void
il3945_rs_get_rate(void *il_r, struct ieee80211_sta *sta, void *il_sta,
                   struct ieee80211_tx_rate_control *txrc)
{
        struct ieee80211_supported_band *sband = txrc->sband;
        struct sk_buff *skb = txrc->skb;
        u8 low = RATE_INVALID;
        u8 high = RATE_INVALID;
        u16 high_low;
        int idx;
        struct il3945_rs_sta *rs_sta = il_sta;
        struct il3945_rate_scale_data *win = NULL;
        int current_tpt = IL_INVALID_VALUE;
        int low_tpt = IL_INVALID_VALUE;
        int high_tpt = IL_INVALID_VALUE;
        u32 fail_count;
        s8 scale_action = 0;
        unsigned long flags;
        u16 rate_mask;
        s8 max_rate_idx = -1;
        struct il_priv *il __maybe_unused = (struct il_priv *)il_r;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

        D_RATE("enter\n");

        /* Treat uninitialized rate scaling data same as non-existing. */
        if (rs_sta && !rs_sta->il) {
                D_RATE("Rate scaling information not initialized yet.\n");
                il_sta = NULL;
        }

        if (rate_control_send_low(sta, il_sta, txrc))
                return;

        rate_mask = sta->supp_rates[sband->band];

        /* get user max rate if set */
        max_rate_idx = fls(txrc->rate_idx_mask) - 1;
        if (sband->band == NL80211_BAND_5GHZ && max_rate_idx != -1)
                max_rate_idx += IL_FIRST_OFDM_RATE;
        if (max_rate_idx < 0 || max_rate_idx >= RATE_COUNT)
                max_rate_idx = -1;

        idx = min(rs_sta->last_txrate_idx & 0xffff, RATE_COUNT_3945 - 1);

        if (sband->band == NL80211_BAND_5GHZ)
                rate_mask = rate_mask << IL_FIRST_OFDM_RATE;

        spin_lock_irqsave(&rs_sta->lock, flags);

        /* for recent assoc, choose best rate regarding
         * to rssi value
         */
        if (rs_sta->start_rate != RATE_INVALID) {
                if (rs_sta->start_rate < idx &&
                    (rate_mask & (1 << rs_sta->start_rate)))
                        idx = rs_sta->start_rate;
                rs_sta->start_rate = RATE_INVALID;
        }

        /* force user max rate if set by user */
        if (max_rate_idx != -1 && max_rate_idx < idx) {
                if (rate_mask & (1 << max_rate_idx))
                        idx = max_rate_idx;
        }

        win = &(rs_sta->win[idx]);

        fail_count = win->counter - win->success_counter;

        if (fail_count < RATE_MIN_FAILURE_TH &&
            win->success_counter < RATE_MIN_SUCCESS_TH) {
                spin_unlock_irqrestore(&rs_sta->lock, flags);

                D_RATE("Invalid average_tpt on rate %d: "
                       "counter: %d, success_counter: %d, "
                       "expected_tpt is %sNULL\n", idx, win->counter,
                       win->success_counter,
                       rs_sta->expected_tpt ? "not " : "");

                /* Can't calculate this yet; not enough history */
                win->average_tpt = IL_INVALID_VALUE;
                goto out;

        }

        current_tpt = win->average_tpt;

        high_low =
            il3945_get_adjacent_rate(rs_sta, idx, rate_mask, sband->band);
        low = high_low & 0xff;
        high = (high_low >> 8) & 0xff;

        /* If user set max rate, dont allow higher than user constrain */
        if (max_rate_idx != -1 && max_rate_idx < high)
                high = RATE_INVALID;

        /* Collect Measured throughputs of adjacent rates */
        if (low != RATE_INVALID)
                low_tpt = rs_sta->win[low].average_tpt;

        if (high != RATE_INVALID)
                high_tpt = rs_sta->win[high].average_tpt;

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        scale_action = 0;

        /* Low success ratio , need to drop the rate */
        if (win->success_ratio < RATE_DECREASE_TH || !current_tpt) {
                D_RATE("decrease rate because of low success_ratio\n");
                scale_action = -1;
                /* No throughput measured yet for adjacent rates,
                 * try increase */
        } else if (low_tpt == IL_INVALID_VALUE && high_tpt == IL_INVALID_VALUE) {

                if (high != RATE_INVALID &&
                    win->success_ratio >= RATE_INCREASE_TH)
                        scale_action = 1;
                else if (low != RATE_INVALID)
                        scale_action = 0;

                /* Both adjacent throughputs are measured, but neither one has
                 * better throughput; we're using the best rate, don't change
                 * it! */
        } else if (low_tpt != IL_INVALID_VALUE && high_tpt != IL_INVALID_VALUE
                   && low_tpt < current_tpt && high_tpt < current_tpt) {

                D_RATE("No action -- low [%d] & high [%d] < "
                       "current_tpt [%d]\n", low_tpt, high_tpt, current_tpt);
                scale_action = 0;

                /* At least one of the rates has better throughput */
        } else {
                if (high_tpt != IL_INVALID_VALUE) {

                        /* High rate has better throughput, Increase
                         * rate */
                        if (high_tpt > current_tpt &&
                            win->success_ratio >= RATE_INCREASE_TH)
                                scale_action = 1;
                        else {
                                D_RATE("decrease rate because of high tpt\n");
                                scale_action = 0;
                        }
                } else if (low_tpt != IL_INVALID_VALUE) {
                        if (low_tpt > current_tpt) {
                                D_RATE("decrease rate because of low tpt\n");
                                scale_action = -1;
                        } else if (win->success_ratio >= RATE_INCREASE_TH) {
                                /* Lower rate has better
                                 * throughput,decrease rate */
                                scale_action = 1;
                        }
                }
        }

        /* Sanity check; asked for decrease, but success rate or throughput
         * has been good at old rate.  Don't change it. */
        if (scale_action == -1 && low != RATE_INVALID &&
            (win->success_ratio > RATE_HIGH_TH ||
             current_tpt > 100 * rs_sta->expected_tpt[low]))
                scale_action = 0;

        switch (scale_action) {
        case -1:
                /* Decrese rate */
                if (low != RATE_INVALID)
                        idx = low;
                break;
        case 1:
                /* Increase rate */
                if (high != RATE_INVALID)
                        idx = high;

                break;
        case 0:
        default:
                /* No change */
                break;
        }

        D_RATE("Selected %d (action %d) - low %d high %d\n", idx, scale_action,
               low, high);

out:

        if (sband->band == NL80211_BAND_5GHZ) {
                if (WARN_ON_ONCE(idx < IL_FIRST_OFDM_RATE))
                        idx = IL_FIRST_OFDM_RATE;
                rs_sta->last_txrate_idx = idx;
                info->control.rates[0].idx = idx - IL_FIRST_OFDM_RATE;
        } else {
                rs_sta->last_txrate_idx = idx;
                info->control.rates[0].idx = rs_sta->last_txrate_idx;
        }
        info->control.rates[0].count = 1;

        D_RATE("leave: %d\n", idx);
}

#ifdef CONFIG_MAC80211_DEBUGFS

static ssize_t
il3945_sta_dbgfs_stats_table_read(struct file *file, char __user *user_buf,
                                  size_t count, loff_t *ppos)
{
        char *buff;
        int desc = 0;
        int j;
        ssize_t ret;
        struct il3945_rs_sta *lq_sta = file->private_data;

        buff = kmalloc(1024, GFP_KERNEL);
        if (!buff)
                return -ENOMEM;

        desc +=
            sprintf(buff + desc,
                    "tx packets=%d last rate idx=%d\n"
                    "rate=0x%X flush time %d\n", lq_sta->tx_packets,
                    lq_sta->last_txrate_idx, lq_sta->start_rate,
                    jiffies_to_msecs(lq_sta->flush_time));
        for (j = 0; j < RATE_COUNT_3945; j++) {
                desc +=
                    sprintf(buff + desc, "counter=%d success=%d %%=%d\n",
                            lq_sta->win[j].counter,
                            lq_sta->win[j].success_counter,
                            lq_sta->win[j].success_ratio);
        }
        ret = simple_read_from_buffer(user_buf, count, ppos, buff, desc);
        kfree(buff);
        return ret;
}

static const struct file_operations rs_sta_dbgfs_stats_table_ops = {
        .read = il3945_sta_dbgfs_stats_table_read,
        .open = simple_open,
        .llseek = default_llseek,
};

static void
il3945_add_debugfs(void *il, void *il_sta, struct dentry *dir)
{
        struct il3945_rs_sta *lq_sta = il_sta;

        lq_sta->rs_sta_dbgfs_stats_table_file =
            debugfs_create_file("rate_stats_table", 0600, dir, lq_sta,
                                &rs_sta_dbgfs_stats_table_ops);

}

static void
il3945_remove_debugfs(void *il, void *il_sta)
{
        struct il3945_rs_sta *lq_sta = il_sta;
        debugfs_remove(lq_sta->rs_sta_dbgfs_stats_table_file);
}
#endif

/*
 * Initialization of rate scaling information is done by driver after
 * the station is added. Since mac80211 calls this function before a
 * station is added we ignore it.
 */
static void
il3945_rs_rate_init_stub(void *il_r, struct ieee80211_supported_band *sband,
                         struct cfg80211_chan_def *chandef,
                         struct ieee80211_sta *sta, void *il_sta)
{
}

static const struct rate_control_ops rs_ops = {
        .name = RS_NAME,
        .tx_status = il3945_rs_tx_status,
        .get_rate = il3945_rs_get_rate,
        .rate_init = il3945_rs_rate_init_stub,
        .alloc = il3945_rs_alloc,
        .free = il3945_rs_free,
        .alloc_sta = il3945_rs_alloc_sta,
        .free_sta = il3945_rs_free_sta,
#ifdef CONFIG_MAC80211_DEBUGFS
        .add_sta_debugfs = il3945_add_debugfs,
        .remove_sta_debugfs = il3945_remove_debugfs,
#endif

};

void
il3945_rate_scale_init(struct ieee80211_hw *hw, s32 sta_id)
{
        struct il_priv *il = hw->priv;
        s32 rssi = 0;
        unsigned long flags;
        struct il3945_rs_sta *rs_sta;
        struct ieee80211_sta *sta;
        struct il3945_sta_priv *psta;

        D_RATE("enter\n");

        rcu_read_lock();

        sta = ieee80211_find_sta(il->vif, il->stations[sta_id].sta.sta.addr);
        if (!sta) {
                D_RATE("Unable to find station to initialize rate scaling.\n");
                rcu_read_unlock();
                return;
        }

        psta = (void *)sta->drv_priv;
        rs_sta = &psta->rs_sta;

        spin_lock_irqsave(&rs_sta->lock, flags);

        rs_sta->tgg = 0;
        switch (il->band) {
        case NL80211_BAND_2GHZ:
                /* TODO: this always does G, not a regression */
                if (il->active.flags & RXON_FLG_TGG_PROTECT_MSK) {
                        rs_sta->tgg = 1;
                        rs_sta->expected_tpt = il3945_expected_tpt_g_prot;
                } else
                        rs_sta->expected_tpt = il3945_expected_tpt_g;
                break;
        case NL80211_BAND_5GHZ:
                rs_sta->expected_tpt = il3945_expected_tpt_a;
                break;
        default:
                BUG();
                break;
        }

        spin_unlock_irqrestore(&rs_sta->lock, flags);

        rssi = il->_3945.last_rx_rssi;
        if (rssi == 0)
                rssi = IL_MIN_RSSI_VAL;

        D_RATE("Network RSSI: %d\n", rssi);

        rs_sta->start_rate = il3945_get_rate_idx_by_rssi(rssi, il->band);

        D_RATE("leave: rssi %d assign rate idx: " "%d (plcp 0x%x)\n", rssi,
               rs_sta->start_rate, il3945_rates[rs_sta->start_rate].plcp);
        rcu_read_unlock();
}

int
il3945_rate_control_register(void)
{
        return ieee80211_rate_control_register(&rs_ops);
}

void
il3945_rate_control_unregister(void)
{
        ieee80211_rate_control_unregister(&rs_ops);
}